Longtime Apple human interface director Greg Christie, who has been with the iPhone maker since 1996, is said to be planning an exit after his relationship with recently-elevated senior vice president of design Jony Ive allegedly turned sour.

Apple SVP of Industrial Design Jony Ive.

Christie is currently responsible for software design across each of Apple's product lines and was a key member of the group that created the first-generation iPhone. He reports to Apple software chief Craig Federighi, rather than nominal design leader Jony Ive, who has until now chosen to eschew day-to-day management of the software design team in favor of providing high-level direction.

That is reportedly set to change, however, with Christie leaving the company and Ive assuming full control of the software group. Word of Christie's impending departure comes from 9to5Mac, who blames tension between Christie and Ive for the split.

The two began working more closely in 2012 after former iOS software head Scott Forstall was pushed out of the company. Notably, Forstall is also said to have had a rocky relationship with Ive, contributing to a downfall that was primarily caused by the disastrous rollout of Apple's in-house mapping initiative.

At the time, sources said that Ive and Christie had "very different styles." Christie is known to speak frankly, though design sessions were said to be "pleasant and cordial," unlike meetings in which Ive and Forstall refused to speak without an intermediary.

Christie's departure, if true, would come just weeks after Apple appeared to begin the process of elevating his profile outside the company. Christie gave an interview in late March, detailing the development of the original iPhone, in which he said that the handset's software vision came together in just two weeks following an ultimatum from late Apple CEO Steve Jobs.

Update: Apple sent a statement to the Financial Times confirming Christie's departure, but failed to elaborate on the details.

Greg has been planning to retire later this year after nearly 20 years at Apple. He has made vital contributions to Apple products across the board, and built a world-class Human Interface team which has worked closely with Jony for many years.

Apple is destroying the fantastic Mac interface with the awkward iOS interface. No labels, no scrollbars, no arrows on scroll bars, etc. Not to mention the hard to read fonts on iOS and the almost invisible slide to unlock. Functionality should be ABOVE the look or plain design, and not the other way round.

Microsoft and Apple are making the same basic mistake--following design fads at the expense of usability. Apple isn't sliding into the abyss quite as fast as MS (who managed to ship an OS with perfect security: no way to access anything), but that's cold comfort.

Apple because became awesome because their team included psychologists who not only helped design the interface, they tested their theories before shipping them. I haven't heard of psychologists on Apple's design team for at least the last 15 years, and it's showing in the interface. (Gray on gray, hidden features--like scroll bars--that actually convey information, etc.)